Multipotent stem cells have become highlighted as therapeutic agents for ischemia, Parkinson's disease, Alzheimer's disease, cardiac infarction, and liver diseases. Stem cells transplanted become effective in treatment of diseases only if the following requirements are met: The first requirement is that stem cells transplanted are differentiated into a cell type of interest. The second requirement is to form networks between differentiated stem cells and surrounding tissues and cells. Regenerative tissue or bone structures involve directed growth of cells to form higher order structures.
However, in the practical realm, stem cells transplanted in injured region are very likely to be washed away with no formation of networks (e.g., neuron networks). To make matters worse, they can migrate to an undesirable region and differentiated into undesirable cell types such as tumors.
Accordingly, there have been made extensive researches to develop scaffolds without in vivo toxicities for stem cell. However, the development of scaffolds without toxicities has been considered a difficult task and the injection of scaffolds into body has been frequently reported to cause adverse effects. Significant issues can arise with carbon nanotubes that have toxic metal elements or salts that come from residual catalysts, such as Cobalt, used to make the carbon nanotubes, clumps or bundles of carbon nanotubes that cannot be used to make scaffolds of uniform structure, and hydrophobic surfaces that do not allow ease of affinity with stem cells and products of their differentiation.
Therefore, there remains a need to develop a novel scaffold having convenient and more effective clinical applicability with no in vivo toxicities.
Throughout this application, several patents and publications are referenced and citations are provided. The disclosure of these patents and publications is incorporated into this application in order to more fully describe this invention and the state of the art to which this invention pertains. A review of several studies is provided in “Carbon Nanotubes for Stem Cell Control”. D. A. Stout and T. J. Webster. Materials Today, July-August 2012, Volume 15, Number 7-8, pp. 312-318, Elsevier.
The present inventors have discovered that a plurality of discrete carbon nanotubes offer novel capabilities to specifically locate and create scaffolds for stem cells without cytotoxicity, thereby allowing networking between differentiated stem cells and tissues present in sites, and hence significant cell therapy efficacy. Cytotoxicity is herein defined as the quality of causing significant or undesirable harm to healthy cells. Without cytotoxicity indicates that significant portions of beneficial cells are not deleteriously affected, killed, or both as a direct result of the scaffolding or composition.
An embodiment of this invention is that the discrete carbon nanotubes in the scaffolding further comprise an amount of functional groups of at least about 1 percent by weight of the dry discrete carbon nanotubes. A plurality of discrete carbon nanotubes can be open ended and substantially cleaned of catalytic residues.
Another embodiment of this invention are scaffold comprising discrete carbon nanotubes, wherein the discrete carbon nanotubes have a length less than 4 micrometers, preferably less than 3 micrometers and more preferably less than 2 micrometers. The length distribution of discrete carbon nanotubes can have a modality, preferably monomodal, most preferably bimodal.
In yet another embodiment of this invention the scaffold further comprises a polymer. The polymer can be selected from a group of polymers that do not exhibit cytotoxity or incite immune response. The polymer may also be selected from a group of polymers that are biodegradable and or water soluble. The polymer further comprises the weight percentage range of about 1 to about 99, preferably less than about 90 percent, more preferably less than about 50 percent and most preferably less than about 10 percent of the scaffold.
A further embodiment of this invention is the discrete carbon nanotubes of the scaffolding further comprise functional groups that increase affinity of biological moieties to the discrete carbon nanotube surface.
A yet further embodiment of this invention is a composition for stem cell therapy, which comprises: (a) a stem cell; and (b) discrete carbon nanotubes serving as a stem cell scaffold without cytotoxicity. The stem cell may be an embryonic stem cell or adult stem cell. The stem cell can also be neuronal stem cell and the composition is one for treating neuronal diseases. The neuronal disease may be selected from the group consisting of neurodegenerative disorder. The neurodegenerative disorder can be selected from the group consisting of Alzheimer's disease, Huntington's disease, Parkinson's disease, motor neuron disease and amyotrophic lateral sclerosis.
Another embodiment of this invention is the composition for stem cell therapy wherein the discrete carbon nanotube is in the form of suspension.
A further embodiment of this invention is a cell therapy method using a stem cell, which comprises administering to an animal a composition for stem cell therapy comprising (a) a stem cell; and (b) discrete carbon nanotubes serving as a stem cell scaffold without cytotoxicity. The stem cell can be an embryonic stem cell or adult stem cell. The stem cell can also be neuronal stem cell and the composition is one for treating neuronal diseases. The neuronal disease may be selected from the group consisting of neurodegenerative disorder. The neurodegenerative disorder can be selected from the group consisting of Alzheimer's disease, Huntington's disease, Parkinson's disease, neural motor disease and amyotrophic lateral sclerosis. The discrete carbon nanotube can be in the form of a suspension.
An additional embodiment of this invention is the use of a composition comprising (a) a stem cell; and (b) discrete carbon nanotubes serving as a stem cell scaffold without cytotoxicity for manufacturing a medicament for cell therapy. The stem cell can be an embryonic stem cell or adult stem cell. The stem cell can also be neuronal stem cell and the composition is one for treating neuronal diseases. The neuronal disease may be selected from the group consisting of neurodegenerative disorder and ischemia-reperfusion injury. The neurodegenerative disorder can be selected from the group consisting of Alzheimer's disease, Huntington's disease, Parkinson's disease and amyotrophic lateral sclerosis. The ischemia-reperfusion injury can be an ischemic stroke. The discrete carbon nanotube can be in the form of a suspension.
It is another object of this invention to provide a composition comprising (a) a stem cell; and (b) discrete carbon nanotubes serving as a stem cell scaffold without cytotoxicity for manufacturing a medicament for cell therapy wherein the scaffold and stem cell for stem cell therapy further comprise a medicant.
Another object of this invention is to provide a composition comprising (a) a stem cell; and (b) discrete carbon nanotubes serving as a stem cell scaffold without cytotoxicity wherein the scaffold is in the form of a foam, fiber or film. The scaffold may further comprise a multilayer.
An additional object of this invention is to provide discrete carbon nanotubes within the scaffold wherein the discrete carbon nanotubes have a least a portion of the discrete carbon nanotubes that are oriented.
Another object of this invention is to provide a method to protect stem cells from damage by encasing the stem cell into a scaffold comprising discrete carbon nanotubes.
An embodiment of this invention is a method to protect stems cells from damage during injection or deposition by encasing the stem cell into a scaffold comprising discrete carbon nanotubes.
Another embodiment of this invention is a composition comprising (a) a stem cell; and (b) discrete carbon nanotubes serving as a stem cell scaffold without cytotoxicity further comprising an inducer for stem cell differentiation.
A further embodiment of this invention is a method to form a stem cell scaffold by admixing a mixture of discrete nanotubes with different functionalities wherein on mixing the nanotubes associate with each other type of functionality.
A yet further embodiment of this invention is a stem cell scaffold comprising discrete carbon nanotubes, and further comprising a surfactant. The surfactant can be anionic, cationic or non-ionic.
Another embodiment of this invention is a stem cell scaffold comprising discrete carbon nanotubes that can be used as an adhesive for tissue, or bone.
In yet another embodiment of this invention the scaffold further comprises a polymer wherein the polymer is selected from a group of biological polymers comprising proteins, peptides, long chain carbohydrates, proteoglycans, or lipids. The polymer can be partly digested or modified. The components of the polymer can be substantially similar to the make-up of the extracellular matrix or an antibody locking the scaffold to lesions or sites of cell damage.
In an additional embodiment of this invention the scaffold further comprises a polymer wherein the polymer is selected from a group of biological polymers comprising chemotactic, wound healing, extracellular matrix producing proteins. The extracellular producing protein can further comprise fibronectin, integrin, or fibrin.